A growing number of reports have described a myopathy to occur in patients with HIV infection, but the prevalence of HIV-associated myositis is unknown. In this study, patients with elevated creatine kinases will undergo EMG's and muscle biopsies. Those found to have inflammatory myopathy will be further examined for potential infectious triggers and genetic factors. In addition, the safety and efficacy of prednisone therapy will be tested in a double-blind trial of prednisone vs placebo.